PORTLAND, Ore. -- More than four dozen searchers were involved indiving into bodies of water on Sauvie Islandon Saturday and divers returned again on Sunday. It's thefirst time searchershave been back on the island in about a month.

Volunteer diver Jayson Cottle drove his own rig, loaded with personal scuba gear, giving up a weekend to help search for Kyron Horman, who disappeared June 4 from Skyline Elementary School.

I m pretty adventurous, Cottle told KGW, I like going and doing unusual things that most people are not interested in.

Officials told KGW that the operation had been planned for several weeks but that they had had to wait for resources to become available from other agencies.

Searchers used sophisticated sonar mapping equpment over the weekend. Why sonar?

Multnomah County Sheriff's Office spokesman Lt. Mary Lindstrand chose words carefully.

They're looking for items, I can't give the specifics and have to be careful in what I say here, she said. They are using the sonar to see if there's something they need to check.

Divers went into the water if the sonar picked up a signal worthy of investigation.

The visibility in the canal is at best three feet today, Cottle said. And as soon as you make a pass, your next next pass is silted up and even worse.

The area has been searched on foot and by divers on and off ever since Kyron Horman went missing.

Kyronwas seven years old when he disappeared. No suspects or persons of interest have ever been formally named in the case, but both of Kyron's parents have stated repeatedly that they believe Terri Horman was involved in the boy's disappearance.

Court filing: Terri's silence implies guilt

On Friday, in court documents, Kaine Horman suggested that Terri Moulton Horman's silence implied guilt regarding Kyron's disappearance. In the papers filed Friday, Kaine asked the court to consider Terri's silence as an admission regarding Father's factual allegations. More:Kaine:Silence implies guilt

Complete Coverage:The search for Kyron Horman

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